Field of the Invention
The present invention relates to fluorochemical compositions that can be obtained by reacting a polyisocyanate compound with at least one particular isocyanate reactive fluorinated polyether compound bearing at least one cationic group, and their use for rendering substrates like paper, textiles and leather oil repellent.
Description of Related Art
Commercially available oil- and/or water repellent compositions are typically based on fluorinated compounds that have a perfluorinated aliphatic group. Such compositions are also described for example in U.S. Pat. No. 5,276,175 and EP-A-435 641. The commercial success of this type of compositions can be contributed to their high effectiveness.
Fluorinated compounds based on perfluorinated ether moieties have also been described in the prior art for rendering fibrous substrates oil- and water repellent. For example perfluorinated polyether compounds have been disclosed in EP-A-1-038 919, EP-A-273 449, U.S. Pat. No. 3,553,179 and U.S. Pat. No. 3,446,761. It was found that previously disclosed compositions based on perfluorinated polyether compounds may not be very effective in rendering substrates oil- and/or water repellent.
An important requirement for the treatment of paper to make it suitable for use in contact with food, is the minimization of any risk of contamination of the packaged food by any substances which are harmful or potentially harmful for human and animal health. The optimum situation is when the paper doesn't contain any harmful substances at all or at least doesn't release harmful substances during its use.
The fluorochemicals should impart the required oleophobic characteristics to the treated paper.
Perfluoroalkyl derivatives are generally mixtures of molecules of different chain length, containing four to twenty carbon atoms. The disadvantage of this kind of chemistry is the difficulty to completely eliminate the undesired, persistent and bioaccumulative pollutants perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). The challenge is to find PFOA/PFOS free fluorochemicals with the same or similar application performance compared to existing products.
The compounds disclosed in WO-03/100158 tried to overcome the obstacles of the prior art and describes fluorochemical compositions comprising a dispersion or a solution of a fluorinated compound, wherein the fluorinated compound is the reaction product of a fluorinated polyether and a polyisocyanate. The here described compositions are useful for rendering fibrous materials oil- and water repellent.
However, it has shown that the compositions described by WO 03/100158 cannot be solubilized or dispersed sufficiently in glycol or glycol/water mixtures, which is necessary in order to apply the fluorochemical composition evenly on fibrous substrates, in particular on paper.
Surprisingly, it was found that an isocyanate-reactive fluorochemical polyether bearing at least one cationic group, when reacted with a polyfunctional isocyanate, provides for a PFOA/PFOS free fluorochemical compound that are extremely good soluble or dispersible in glycol or glycol/water mixtures and can therefore by applied evenly on fibrous substrates and that show afterwards unexpected good performance in respect to oil- and/or water repellency, in particular when used on paper.